Compilare: user.cpp: In function ‘bool is(int)’: user.cpp:24:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < h[r].size(); ++i) ^ user.cpp:25:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if( h[r][i] == x ) return 1; ^ user.cpp: In function ‘int main()’: user.cpp:30:33: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("abc2.in","r",stdin); ^ user.cpp:31:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("abc2.out","w",stdout); ^ user.cpp:36:24: warning: ignoring return value of ‘char* fgets(char*, int, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] fgets(s,NMax,stdin); ^ user.cpp:33:13: warning: ‘T’ may be used uninitialized in this function [-Wmaybe-uninitialized] int i,N,T; ^